If your husband's L1 application for extension is denied, you will have no more than 180 days before you are supposed to leave the United States. Assuming you leave when asked, then you are absolutely allowed to apply for a different type of visa (eg - a B2 visa, which is a visitor visa). The amount of time you are authorized to stay in the United States will obviously vary based on the type of visa you are approved for.
Since you paid the extra fee for premium processing, you should have an answer within a couple weeks of the filing date. If your husband's application is denied, make sure you do not stay in the country longer than you are supposed to (eg - 180 days). If you overstay, then from the time you finally leave, you will have to wait 5 years before you are eligible to apply for another visa. Best of luck.
To clarify the previous answer - you are not legally authorized to stay in the US for any time after the I-94 expires or the extension is denied, whichever comes later. You will not be subject to the bar on returning to the US if you overstay by less than 180 days, but you will be out of status. If you need to stay in the US to pack up, sell a house, etc, you could apply to change to B-2 status before the L-1 expires, if the timing works out. If you overstay by 180 days, the bar is 3 years.